LONDON--The piano used to play the glissando that kicks off ABBA's disco hit "Dancing Queen" will be one of the star attractions at a rock and pop auction at Sotheby's next month where it is expected to sell for up to 800,000 pounds ($1.24 million). The instrument comes with a certificate of authentication from ABBA co-founder Benny Andersson, who describes it as "one of a kind and a great source of inspiration." It was designed by Swedish instrument-maker Georg Bolin and comes from the collection of Atlantis Grammofon, formerly known as Metronome Studios, in Stockholm where ABBA recorded the song released in 1976, Sotheby's said on Thursday. Bolin's piano was built for the American jazz pianist and composer Bill Evans, who died in 1980. It was described in the New York Times in 1964 as a "Space-Age piano" that "gives the pianist the sensation of playing 'directly on the strings' as a guitarist would," Sotheby's said. "The piano itself is an instrument of real importance and with the added ABBA provenance we expect it will have worldwide appeal," Philip Errington, Sotheby's Specialist in Books and Manuscripts, said in a statement. The London sale is scheduled for Sept 29. Sotheby's said John Lennon's Steinway upright piano, on which he composed "Imagine", sold for 1.67 million pounds in 2000 while the upright piano in Rick's Cafe in the movie "Casablanca" sold for $3.4 million in 2014.